For a gas turbine engine that employs an annular combustor with radial fuel injection, it has long been known that achieving uniform annular circumferential swirl of fuel and air downstream of the primary combustion zone provides a much more uniform mix to provide a more uniform burn. This results in more annular circumferential uniformity in the turbine inlet temperature. It has been common to provide cooling strips along the inner and outer annular walls, as well as the dome, of the combustor to facilitate this annular circumferential swirl. Such cooling strips baffle air that flows through adjacent film cooling holes in a generally annular circumferential direction. The film cooling holes release pressurised air.
Although these cooling strips are effective in facilitating good fuel and air mixing and enhancing fire spinning within the combustor, the efficiency of the swirling effect provided by the flow of the air through the film cooling holes is prohibited by the strips. This is because the strips cause cooling air momentum loss, thereby reducing efficient mixing of the fuel and air.
Consequently, the maximum turbine inlet temperature may run higher than necessary and turbine life is thereby shortened. It would be desirable to eliminate the adverse impact of the cooling strips on swirling efficiency of the film cooling holes whilst retaining their beneficial impact on the fuel and air mixing and the fire spinning within the combustor.